tropometer

from The Century Dictionary.

• noun An instrument for measuring the degree of rotation or of torsion in a part; one form is used to determine the amount of rotation of the eyeball, another to measure the torsion in one of the long bones.
• noun In horology, a chronometer the dial of which is graduated according to a decimal system of time-notation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An instrument to measure torsion or rotation.